Farmed salmon with no experience of the world outside line up with the Earth’s
magnetic field in the direction of their ancestral feeding grounds, a study
has revealed.

The scientists behind the research said that the fish inherit a “built-in GPS”
that always points them home.

Nathan Putman, from Oregon State University, who led the study, said: “In
essence, the fish act as though they have a map based on the magnetic field.
When the fish experience a magnetic field that is north or south of their
typical ocean range, they change their swimming direction to go back.”